During the financial crisis, it seems everyone became a self professed financial expert. This is not an insightful comment, this is barroom economics.
"Bundle a bunch of bad loans". How? Do you know how a CDO is structured? What is a bad loan exactly? The word "bad" is assuming the consequent. What banks did was aggregate risky loans into structure product, and form tranches. This procedure allows investors with different risk appetite to essentially offer credit to risky borrowers. Yes, the modelling of CDO was poor, and the pumping of liquidity by the fed in the short term lending market didn't help, neither did the guarantee offered by Fannie Mae and Freddie Mac for MBC.
"Sell them claiming their good loans". To whom and how? It's not like the product was secretive or anything. Caveat emptor. Did it help that rating agencies are an oligopoly that prevented competitive rating of bond quality? Hell no! Does it mean that the banks had a sure fire way of making money? No!
Bet money that they'll fail? You're probably referring to Goldman here.... hum funny but that didn't happen. How about reading the case?
Laying off a bunch of worker so that the stock price jump? Wow that's magic. Why exactly the stock price jumps if you're laying worker obviously doesn't need an explanation, just a conceited approving nod I guess.
Summary: if you don't know shit about finance, shut the fuck up.